Displays are ubiquitous and are a core component of many wearable electronic devices, smart phones, tablets, laptops, desktops, TVs and display systems. Common display technologies today range from Liquid Crystal Displays (LCD's) to more recent Organic Light Emitting Diode Displays (OLEDs).
Display architectures include passive and active matrix displays depending on whether each pixel is driven separately or not. Active drive circuitry uses thin film transistor (TFT) technology where transistors based on amphorous, oxide or polysilicon technology are manufactured on glass panels which may have glass substrate sizes from the 1st generation of 30 cm×40 cm to the 10th generation (known as GEN10) of 2.88 m×3.15 m.
However, in most portable devices (i.e. battery powered devices) the display uses the majority of the available battery power. Additionally, the most common user issue for portable devices is insufficient display brightness. To extend battery life and improve brightness levels, it is may be desirable to reduce power consumption and produce higher luminance emission from the light source.
Inorganic light-emitting diode (ILED) displays are emerging as the next generation of flat display image generators providing superior battery performance and enhanced brightness. The ILED display is, at a basic level, a variation of the organic light-emitting diode (OLED) display. OLEDs pass current through organic or polymer materials that are sandwiched between two glass planes to produce light. ILEDs replace the organic LED material with a discrete standard LED (which is made of inorganic materials) at each pixel of the display (each pixel consists of three individual Red, Green and Blue LEDs for color displays).
Standard (i.e. inorganic) LED devices have been around for many years and their performance (efficiency, brightness, reliability and lifetime) has been optimized over many years as the LED industry has pursued many commercial opportunities—especially the challenge of developing LED technology to enable it to replace the standard incandescent bulbs for general light applications, i.e. inorganic LEDs are significantly more efficient, bright and reliable than the new and less developed OLED materials.
The concept of individually switchable standard LEDs (R, G & B) at each pixel in a display is well known. This approach is in widespread use for large information displays. However, to-date it has not been possible to scale this approach down to smaller displays as standard LEDs are typically planar chips which are inefficient for light direction control. Additionally, the assembly of the many millions of pixels needed for a laptop or smart phone display is not feasible using standard assembly manufacturing techniques.